1. Field of the Invention
The invention relates to methods and apparatus for maximizing throughput between objects, of a physical quantity having a substantially unimodal throughput profile in terms of relative orientation of such objects. Examples include an alignment and position stabilization of optical fibers, light sources and fibers, fibers and light input devices, semiconductor wafers and microlithographic photo masks, electrical, tunneling and atomic force microprobes and their substrates, spatial filters and free-space laser beams, pinholes and focused beams, laser plasma tubes and external cavity resonators, to name but a few examples.
2. Information Disclosure Statement
The following disclosure statement is made pursuant to the duty of disclosure imposed by law and formulated in 37 CFR 1.56(a). No representation is hereby made that information thus disclosed in fact constitutes prior art, inasmuch as 37 CFR 1.56(a) relies on a materiality concept which depends on uncertain and inevitably subjective elements of substantial likelihood and reasonableness and inasmuch as a growing attitude appears to require citation of material which might lead to a discovery of a pertinent material though not necessarily being of itself pertinent. Also, the following comments contain conclusions and observations which have only been drawn or become apparent after conception of the subject invention or which contrast the subject invention or its merits against the background of developments which may be subsequent in time or priority.
Also, no preamble of any statement of invention or claim hereof is intended to represent that the content of that preamble is prior art, particularly where one or more recitations in a preamble serve the purpose of providing antecedents for the remainder of a statement of invention or claim.
On Jun. 24, 1983, the Fondation Suisse Pour La Recherche En Microtechnique filed the Swiss Patent Application CH 3444/83 which formed the basis for their European Patent Application 84810298.4, filed Jun. 21, 1984 and published Jan. 9, 1985 under publication number 0,130,6,944, for a method of alignment of a wave guide. Reference may also be had to their corresponding Canadian Patent 1 247 845, issued Jan. 3, 1989, and to articles by T. Edye et al, entitled "Automatic Alignment Station for Single or Multimode Optical Fibers", and "Automatic Assembling Station for Guided Optic Components," SPIE Vol. 483, Optical Alignment II (1984), pp. 65 to 75.
Briefly, that method of alignment imposes a movement to either the excitation unit or the wave guide, which follows a loop in a plane transverse to a connection axis of the wave guide and the excitation unit. Maximum and minimum values of the excitation function are measured by analog circuitry which provides instantaneous orthogonal components of the throughput profile gradient. The other element is moved along these axes until the components of the gradient are zero, when alignment has been achieved.
A similar approach is apparent from U.S. Pat. No. 4,720,163, by John C. Goodwin et al, issued Jan. 19, 1988, for a laser-fiber positioner. Reference may in this respect also be had to an article by John C. Goodwin, entitled "Dynamic Alignment of Small Optical Components", Journal of Lightwave Technology, Vol. LT-5, January 1987, pp. 97 to 101.
Apparatus according to these prior disclosures have been manufactured and are in operation. An automatic alignment for single mode fibers and integrated optical devices has been provided by PHOTON CONTROL LIMITED, as apparent from their brochure entitled NANOTRAK, which mentions that they are using a radar tracking technique known as "Conical Scanning," whereby a servo controlled system continually positions a source on target.
One problem with these systems is lack of versatility, which in effect limits the utility of each apparatus produced pursuant to the above mentioned prior disclosures practically to the given application for which it was specifically designed.